Street sheet pavement or roadway.



-PATENTBD uMAY 5, 1903.

P. J. WARREN. STREET SHEET PAVEMENT 0B. ROADWAY. APPLICATION FILED MAR. 20. 1902.

Patented May 5, 1903.

PATENT OFFICE.

FREDERICK J. WARREN, OF NEWTON, MASSACHUSETTS.

STREET SHEET PAVEMENT-OR ROADWAY.

SPECIFICATION forming part of Letters Patent No. 727,510, dated May 5, 1903.

Application led March 20,1902. Serial No. 99,126. (No specimens.)

To ctZZ w/tom zit may concern."

Be it known that I, FREDERICK J. WARREN, a citizen of the United States, residing atNewton, in Jthe county of Middlesex and State of Massachusetts, have invented a new and usefullmprovement in Street Sheet Pavements or Roadways, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification, in explaining its nature.

The invention is an improvement upon that described in my Letters Patent of the United States No. 675,430, dated June 4, 1901, and upon that described in my Letters Patent No. 695,421, dated March 11, 1902. In the said Patent No. 675,430 I have described a structure for the wearing layer of street sheetpavements, one of the essential features of which is the employment of elements of a stony or mineral nature of predetermined sizes and proportions, designed to provide an inherent stability regardless of the bituminous medium which fills the voids of the structure. A pavement or structure of this character varies from structures heretofore used for the wearing layers of street sheet-pavements in that it is designed that the Wear of traffic shall be borne by the mineral ingredients and that the bituminous binder shall act to seal the interstices in the mineral ingredients rather than to receive the Wear of traffic.

The present invention consists in a structure or the wearing layer of a street sheet pavement or roadway having largely the advantages of the structure ofthe patent, but varying from itand from the structure of the said Letters Patent No. 695,421 referred to in that the sizes of the elements constituting the mineral base differ from those described in either of'said Letters Patent, for I have ascertained that while ,the sizes and proportions of the elements of the mineral base described in the Patent No. 675,430 probably secure a mineral body. of the highestrinherent stability, which eliminates substantially the largest percentage of voids and requires practically the smallest percentage of bituminous medium to till the voids and Weather and water proof the wearing layer, still a very desirable and stable mineral base Will be obtained by suitably combining mineral elements which vary from about one-tenth of an inch in diameter to a diameter from two to three inches. The proportions of the sizes of these elements should be aboutas follows; but any reasonable variation in these proportions which Will not aect theinherent stability of the body of mineral elements may be made Withoutv departing from the spirit of the invention: Of elements which will pass a screen having oneeighth-inch mesh and lodge on a screen of one-tenth-inch mesh, about ten per cent.; of elements which will pass a screen having one-fourth-inch mesh and lodge on a screen of one-eighth-'inch mesh, about ten percent.; of elements which will pass a screen having three-fourths-inch mesh and' lodge on a screen of one-fourth-inch mesh, about fifteen per cent.; of elements which will pass a screen having two-and-one-half-inch mesh and lodge on a screen of three-fourths-inch mesh, about sixty-tive per cent. To a body of one hundred parts of ingredients and bituminous composition there would be from about eighty-seven to ninety per cent. of mineral matter and from thirteen to ten per cent. of bituminous composition. This would depend somewhat upon the constituency and character of the bituminous composition.

While I have spoken of screens having a certain mesh as indicating the size of the mineral elements used, I would say, of course, that a modification in the sizes of the mesh which would produce substantially a stable mineral composition of the character specified could be used.

The mineral structure thus provided will have a larger percentage of voids than that of the Patent No. 675,430, and even of the said Patent No. 695,421, and Will require a larger percentage of bituminous medium to fill the insterstices and Water and Weatherproof the pavement; but still the inherent stability which is a distinguishing feature of my invention will be secured, and thisis due `because of the sizes of the ingredients used, the proportions of such sizes employed, and the large quantity provided compared with the relatively small quantity of bituminous composition.

I will now describe the invention in con- IOO junction with the drawing forming a part of this specification, where the figure represents in a conventional way a section of a street sheet-pavement having the features of my invention.

Referring to the drawing, A represents a conventional subfoundation of a pavement or roadway, and to it is applied the wearing layer B, to which my invention relates. The subfoundation may consist of stony elements of any desired size and may be suitably prepared by `heavy rolling and by coating with a bituminous composition which is adapted to receive the wearing layer and unite it with the subfoundation. The mineral elements composing the wearing layer are coated with the bituminous composition and spread uni-Y formly over the subfoundation to any desired depth and then compressed and consolidated thereon by means of heavy pressuresuch, for instance, as that obtainable by the use of a fifteen or twenty ton steam-roller.

represents the mineral elements of the larger size, and b of the smaller size. The mineral elements are carefully graded as to size by screening and are then proportioned to each other by measuring or weighing and are then combined in a mixer with a sufficient quantity of plastic bituminous composition to thoroughly coat all their individual particles and pieces, enough plastic bituminous composition being used to completely fill all the voids in the wearing layer when the layer is rolled to completion upon the subfoundation. It is desirable that the mineral elements and bituminous composition should be heated to about 200o Fahrenheit first, although this is not absolutely essential, and that it should be laid, rolled, and consolidated at about that temperature.

The coated mineral ingredients generally form a wearing layer from two to three or four inches in thickness, and when solidified upon the subfoundation by heavy pressure a wearin g-section to the pavement is obtained which presents to traffic an area or surface of a stony nature much larger than that of the bituminous composition, and which stony elements are so associated with each other as to form a stable body which receives the wear of traffic and is not dependent upon the bituminous composition or uniting medium for furnishing such stability. These elements not only act to receive the wear of traffic and support itbut they also serve to protect the bituminous composition from the action of the Weather, because only so much of the bituminous composition is exposed as appears at the joints between the mineral components. A

pavement of this character has many advantages over the ordinary asphalt pavement. It is cheaper to construct, far less slippery in use, harder at high temperatures, less liable to crack at low temperatures, does not have so high an expansible or contractible tendency to heat or cold, as the stony elements do not expand or contract, and the proportion of bituminous composition is so small and so disseminated as to practically eliminate this defect in asphalt street-pavements from it.

Having thus fully described my invention, I claim and desire to secure by Letters Patent of lthe United Statesl. A wearing layer of a street sheet-pavement comprising a mineral body composed of stony elements onetenth inch in diameter upward to about two or three inches in diameter and ot' about the proportions indicated, to provide a mineral base or body having inherent stability, uniformly associated t0- gether and combined with a bituminous composition.

2. The method of producing a street sheetpavement consisting in selecting mineral ingredients of grades varying from one-tenth inch to two or three inches, proportioning and mixing the same about as indicated to give the mineral structure an inherent stability, thoroughly mixingv with a bituminous cement before laying and then laying and applying heavy pressures.

3. The method of producing a street sheetpavement consisting in selecting mineral ingredients of grades varying from one-tenth inch to two or three inches, proportioning and mixing the same about as indicated to give the mineral structure an inherent stability, thoroughly mixing with a bituminous cement before laying and then laying and forcing into place at pressure as high as that produced by fteen to twenty ton rollers.

4. A wearing layer of a street sheet-pavement composed of minerals in about the following grades and proportions, elements passing two-and-one-half-inch mesh and stopping at three-fourths-inch mesh sixty-five per cent., elements passing three -fourths-inch mesh and stopping at one-fourth-inch mesh fteen per cent., elements passing one-fourth-inch mesh and stopping at one'eighth-inch mesh ten per cent., elements passing one-eighthinch mesh and stopping at one-tenth-inch mesh, ten per cent.

5. A wearing layer of a street sheet-pavement composed of minerals in about the following grades and proportions, elements passing two-and-one-half-inch mesh and stopping at one-fourth-inch mesh about eighty per cent., elements passing one-fourth-inch mesh about twenty per cent.

6. A wearing layer of a street sheet-pavement composed of minerals in about the following grades and proportions, elements passing two-and-one-half-inch mesh and stopping at one-fourth-inch mesh about eighty per cent., elements passing one-fourth-inch mesh about twenty per cent. in combination with a bituminous cement for uniting said minerals.

7. A wearing layer of a street sheet-pavement composed of minerals in about the following grades and proportions, elements passing two-and-one-half-inch mesh and stopping IOO IOS

IIO

at three-fourths-inch mesh about sixty-five per cent., elements passing three-fourthsinch mesh about thirty-five per cent.

8. A Wearing layer of a street sheet-pavement composed of mineral elements about sixty-five per cent. of which pass a two-andone-half-inch mesh and stop at three-fourthsinch mesh, in combination with a bituminous cement for uniting said minerals.

9. A wearing layer of a street sheet-pavement composed of minerals in about the following grades and proportions, elements passing three-fourths-inch mesh about thirty-five per cent., elements from three-fourths-ineh mesh size upward about sixty-five per cent.

' l0. A Wearing layer of a street sheetpave ment composed of minerals in about the following grades and proportions, elements passing three-fourths-inch mesh about thirty-five per cent., elements from three-fourths inch in size upward about sixty-live per cent., in combination with a bituminous cement for uniting said elements.

11. A Wearing layer for a street sheet-pavement comprising mineral ingredients of several grades `so proportioned and mixed as to give the mineral structure an inherent stability in combination With a bituminous cement composingr only about ten to thirteen percent. of the Volume of the mixture.

FREDERICK Je. WARREN. In presence of-i F. FyRAYMoND, 2d,

J. M. DoLAN. 

